Cushioning and flow control valve



J. S. PILCH CUSHIONING AND FLOW CONTROL VALVE Filed May 17, 1960 ww@@Wawy Lv July l1, 1961 United States Patent 2,991,759 CUSHIONING ANDFLOW CONTROL VALVE John S. lilch, Ware Machine Works, Inc.,

` P.O. Box '140, Ware, Mass.

Filed May 17, 1960, Ser. No. 29,755 Claims. (Cl. 121-40) This inventionrelates to a new and improved boom cushioning and flow control valve forhydraulic systems and to a hydraulic system employing said valve and hasparticular reference to a new and improved valve and hydraulic systemfor controlling the movement of various mechanisms such as the boom on ahydraulic trencher, the push arms on a hydraulic loader, or any otherhydraulic circuit.

An object of the invention is to provide a new and improved valve andhydraulic system of the type set forth which acts as a positive sealwhen the unit is not in operation to eliminate the load creepingdownward, or if the -levers on the main control valve were accidentallyport'26 to the down side of the lift cylinder through line moved whilethe hydraulic pump was not operating, the valve of the present inventionwill eliminate the possibility of oil escaping from the cylinder inquestion which would cause the mechanism to drop downward.

Another object is to provide a valve and system of` the type set forthwhich, when the control valve is moved to lower the load, starts thelowering operation gradually and without a sudden burst of speed.

Another object is to provide a device of the type set forth whichcushions the end of the travel of the apparatus.

Other objects and advantages of the invention will be apparent lfrom thefollowing description taken in connection with the accompanying drawing.

Referring lto the drawing: I f

FIG. 1 is a longitudinal sectional view of a hydraulic cylinderembodying the present invention;

' FIG. v2 is a fragmentary sectional view illustrating a step in theoperation of the device;

FIG. 3 is a fragmentary sectional view, generally similar to FIG. 2, butillustrating another step in the operation of the device; and

FIG. 4 is a schematic view of a hydraulic system embodyingthe invention.

Referring more particularly to the drawing wherein similar referencecharacters designate corresponding parts l throughout, the hydraulicsystem shown in FIG. 4 comprises a main `control valve 10 adapted toreceive hydraulic lluid under pressure through hydraulic line 11 andhaving an outlet 12 connected =by hydraulic line 13 to port 14 on thedown side of cylinder 15. Hydraulicline v13 is also connected 'by theline 16 to the port 17 in the end of cylinder 18. Cylinder 18 has theport 19,connected by hydraulic line 20 to the port 21 on control valve10. Cylinder 18 has the portion 18a with port 18b which is connected byhydraulic line 21 to port 22 `on-the lift side of cylinder 15. l v Incylinder 15 is provided the double acting piston 23 connected to the ram24.

In port 17 of cylinder 18 is provided the member 2 5 having the pilotorifice 26 as hereinafter described. In f cylinder 18 is provided thecushion timing piston 27 which has the Q ring seal 28 in its periphery.

The piston 18 is provided with the end cap 18e having the extensionportion 18a and in end cap 18e` is provided a seat 29 for cushioningvalve 30 which is provided at its end adjacent timing piston 27 withports 31 which are always adapted to be positioned beyond the end ofseat 29.

'Cushioning valve 30 has the spring seat portion 32 engaging coil spring33 which has its opposite end engaging the inner surface of threaded cap3:4` andfon the side ice Patented `July 11, 1961 of cushioning valve 30opposite spring seat 32 are prof vided the ports or passages 35.

It will belnoted that the ports 35 are graduated in size and are spacedfrom each other a considerable distance and these ports could 'bereplaced by one long tapered slot in order that the plunger open theproper distance depending upon the volume of fluid being supplied by thepump which eliminates jerky movement of the equipment and assures theelimination of vacuum in the cylinder.

With the present device, as the operator lowers his load, the cushiontiming piston 27 is in the position shown in FIG. 1 and as the operatormoves the main control valve into hold position, closing oli the linesfromv the cylinder to the oil reservoir there would be a sudden jar if aheavy load on the end of a boom or a loader bucket full of material wasstopped suddenly. With the present valve, as the load attempts to comedown, this load creates pressure on the -lift side of the lift cylinderforcing fluid through port 19 and through ow control cushioning plunger30 gradually moving the cushioning timing piston to the left and iluidthenwould flow through 13 and port 14. As this operation continues, oilwould beescaping on a graduated scale because of the graduated ports ororifices 35 and as soon as the cushion timing piston 27 has traveled tothe Ifull extent on theleft;2 the plunger would be closed as shown inFIG, 3, and the boom could not `travel downward any more. It can =beclearly seen that with the use of this valve, after theV oper@ ator hasmanually closed oif the main control valve'10, the trencher boom orloader arms can travel downward a a predetermined distance and at agraduated pace and be automatically brought to a smooth stop. The valveof the present invention actsV as a positive seal by preventing Huidpassing and/ or leaking from the lift side lof `the lift cylinderthrough ythe main control valve 10 and this prevents the trencher -boomfrom creeping downward while the trencher is not -inruse, and even moreimportantly, acts as a safety device by preventing the boom fromdropping if any person moves the control handle of control valve 10while thetrencheris not in use. The operation of the valve as a positiveseal is as follows y' At all times, when the main control valve sclosed, the flow vcontrol plungery 30 is closed against seatv 2 9, seeFIG. 3, bypressure exerted from the lift side of the -li-ft cylinderthrough line 21 and port 181;. This prevents oil passing out of the liftside of the lift cylinder if the main control valve leaks or is openedaccidentally while the trencher is not running. l

The ow control plunger 30 is unseated to connect po'rt 22.with the maincontrol valve only when hydraulic pressure from the pump is applied -tothedown side fof the lift cylinder 15. This pressure passes from port 12to port .14 through line 13 into the down side'ofthelift cylinder 15 andexerts pressure against the lift'cylinder piston 23. `The lift cylinderpiston 23 is unable to ymove at that moment because line 21 is closed byseated plunger 30. This pressure being applied to the down side of liftcylinder 15 also passes through line 16 through pilot orifice 26 andpushes cushion timing piston 27 tothe right which in turn pushes flowcontrol plunger 30V to the right unseating the same and allowing fluidto How from port 22 to the main control Valve. i*

As stated above, the valve also acts as a cushioning valve when startingto lower the trencher boom. As explained above, when hydraulic pressureisY applied tothe down side of cylinder 15, iluid cannot escape from thelift side of lcylinder 15 until iluid from the down side :of saidcylinder has passed through the pilot orice 26. and moved the cushiontiming piston 27 to the right, thereby unseating plunger 30.VA .Asplunger 30 begins to unseat iluid ows through the graduated orifices orports 35, completing the circuit -from port 22 to the main controlvalve. The oriices or ports 35 being graduated, restrict the ow of fluidat first and then as each is opened, allow more uid to ow until theirtotal area is more than that of the lines in the system and completefull ilow is accomplished. This graduated restriction, from no ow tofull ilow, when done in a short period of time, acts as a cushion andbecause of this, the trencher boom starts to move downward very slowlyand then gradually speeds up to fyull downward speed making downwardoperation smooth and free of jerks.

The valve, as statedabove, also acts as a cushioning valve when stoppingdownwardmovement of the trencher boom. In this arrangement, when theboom is being lowered, pressure applied to the down side of the liftcylinder holds the dow control and cushioning plunger 30 open, asdescribed above in connection with the action of the valve as a positiveseal, and when the operator closes the main control valve to stopdownward movement, the owing cycle takes place which cushions thestopping of the downward movement of the trencher boom and associatedparts:

The closing of the main control valve by the operator stops the ow offluid through lines 13 and 11 and due to the momentum and weight of theboom and associated parts, pressure is exerted on the lift side of thelift cylinder 15, while the pressure immediately drops on the down sideof the lift cylinder.

The pressure already present between piston 27 and orifice 26 escapesthrough pilot orifice 26 through lines 16 and 13 to the down side of theliftcylinder 15, thereby lowering the pressure in the chamber betweenpiston 27 and pilot orifice 26 and as this pressure drops, pressure fromthe lift side of the lift cylinder is exerted on the side of piston 27opposite pilot orice 26 by owing through the orices 35 in the ow controlplunger 30 and causing the cushion timing piston 30 to move towardpiston 27. Pressure on the right side of timing piston 27 and on theright end of flow control plunger 30 keeps the cushion timing piston 27moving toward orice 26 and due to the graduated orifices in the owcontrol plunger 30, the more the cushion timing piston 27 moves to theleft, the more the restriction until the iiow control plunger 30 isfully seated as shown in FIG. 3. This graduated cutdown of ow cushionsthe downward movement of the trencher boom and it is gradually broughtto a stop.

The ow control valve also acts to provide anti-cavitation to the downside of the lift cylinder during downward movement of the trencher boom.VIn this operation, as the trencher boom is being lowered due to theweight of the trencher bucket, dipper stick, etc., there is a tendencyfor the fluid from the lift side of the lift cylinder to escape at afaster rate than the pump through the manual control valve suppliesfluid to the down side of the lift cylinder 15. With the present valve,as shown in FIG. 3, uid from the lift side of the cylinder cannot escapeuntil line 16 is pressurized and tluid pressure that is escaping fromthe lift side of the lift cylinder piston is attempting to keep plunger30 closed. The pump supplying iluid to the down side of the liftcylinder 15 and pressurizing line 16, dueto the cushion timing pistonbeing larger in diameter than the ilow control and cushioning plunger30, forces the cushion timing piston Z7 to move to the right and openplunger 30 and keeps it open only as long as there is pressure in line16. It will be understood that plunger 30 is opened only the properdistance or amount, as an example, if the motor were idling and the pumpwere turning out only a small volume of fluid then the plunger 30 mightconceivably be moved over very little a's the rst few orices 35 would belarge enough to take the ow of uid being supplied 4by the pump whereas,if the pump were running at a Vhigher pace, plunger 30 would be 'moved agreater distance tothe right and ,So on and, therefore, at Ano time 4 Ican line 16 be under a vacuum which would allow the pump to cavitate.

From the foregoing, it will be seen that I have provided new andimproved means for obtaining all of the objects and advantages of theinvention.

I claim:

1. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice for controlling the passage of fluid tosaid cylinder on one side of said piston, a uid passage connected tosaid cylinder on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite `saidrestricted oritice, a valve for controlling the passage of fluidv `fromsaid cylinder to said chamber, said valve being adapted to be moved inone direction by said piston, resilient means for normally urging saidvalve in a direction opposing movement thereof by said piston, and saidvalvehaving a passage therethrough connecting said cylinder with saidchamber, and port means in said chamber adapted to be connected to ahydraulic line.

2. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice -for controlling the passage of fluid tosaid cylinder on one side of said piston, a uid passage connected tosaid cylinder on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite saidrestricted orice, a valve for controlling the passage of fluid from saidcylinder to said chamber, said valve being adapted to be moved in onedirection by said piston, resilient means for normally urging said valvein a direction opposing movement thereof by said piston, and s aid valvehaving a passage therethrough connecting said cylinder with saidchamber, said valve having port means of progressively increasing areaas said valve is moved into into said chamber by said piston, and portmeans in said chamber adapted to be connected to a hydraulic line.

3. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice for controlling the passage of uid tosaid cylinder on one side of said piston, a uid passage connected tosaid cylinder `on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite saidrestricted orifice, a valve for controlling the passage of fluid fromsaid cylinder to said chamber, said valve being adapted to be moved inone direction by said piston, resilient means for normally urgingsaid'valve in a direction opposing movement thereof by said piston, andsaid valve having a passage therethrough connecting said cylinder withsaid chamber and port means in said chamber adapted to be connected to ahydraulic line.

4. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice for controlling the passage of fluid tosaid cylinder on one side of said piston, a Huid passage connected to,said cylinder on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite saidrestricted orifice, a valve for controlling the passage of uid from saidcylinderto said chamber, said valve being adapted to be moved in onedirection by said piston, resilient means for normally urging said valvein a direction opposing move rnent thereof by said piston, and said valve having a passage therethrough connecting said cylinder with saidchamber, said valve having port means of progressively increasing areaas said valve is moved into said chamber by said piston and port meansin said chamber adapted to be connected to a hydraulic line. i

`5. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orice for controlling the passage of uid to saidcylinder on one side `of said piston, .a fluid passage connected to saidcylinder on the `opposite side of said piston, a chamber communicatingwith said cylinder on the side thereof opposite `said restricted orice,a valve for controlling the passage `o f uid lfrom said cylinder to saidchamber, said valve being adapted to be moved in one direction by saidpiston, resilient means for normally urging said valve in a directionopposing movement thereof by said piston, and said valve having apassage therethrough connecting said cylinder with said chamber, saidvalve being adapted to be closed by said resilient means and opened bythe force of fluid in said cylinder from a hydraulic line and passingthrough said restricted orifice, and port means in said chamber adaptedto be connected to a hydraulic line.

6. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice for controlling the passage of fluid tosaid cylinder on one side of said piston, a fluid passage connected tosaid cylinder on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite saidrestricted orifice, a port in said chamber, a valve for controlling thepassage of fluid from said cylinder to said chamber, said valve beingadapted to be moved in one direction by said piston, resilient means fornormally urging said valve in a direction opposing movement thereof bysaid piston, and said valve having a passage connecting said cylinderwith said chamber, sai-d restricted orifice being connected by ahydraulic line to the control valve and the down side of a cylinder andsaid port in said chamber being connected by a hydraulic line to thelift side of a cylinder with said fluid passage on the side of saidcylinder opposite said restricted orifice being connected to the controlvalve.

7. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice for controlling the passage of fluid tosaid cylinder on one side of said piston, a fluid passage connected tosaid cylinder on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite saidrestricted orice, a port in said chamber, a valve for controlling thepassage of fluid from said cylinder to said chamber, said valve beingadapted to be moved in one direction by said piston, resilient means fornormally urging said valve in a direction opposing movement thereof bysaid piston, and said valve having a passage connecting said cylinderwith said chamber, said valve having port means of progressivelyincreasing area as said valve is moved into said chamber by said piston,said restricted orice being connected by a hydraulic line to the controlvalve and the down side of a cylinder and said port in said chamberbeing connected by a hydraulic line to the lift side of a cylinder withsaid fluid passage on the 'side of said cylinder opposite saidrestricted orifice being connected to the control valve.

8. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice for controlling the passage of fluid tosaid cylinder on one side of said piston, a fluid passage connected tosaid cylinder on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite saidrestricted orice, a port in said chamber, a valve for controlling thepassage of fluid from said cylinder to said chamber, said valve beingadapted to be moved in one direction by said piston, resilient means fornormally urging said valve in a direction opposing movement thereof bysaid piston, and said valve having a passage connecting said cylinderwith said chamber and port means in said chamber adapted to be connectedto a hydraulic line, said restricted orifice being connected by ahydraulic line to the control valve and the down side of a cylinder andsaid port in said chamber being connected by a hydraulic line to thelift side of a cylinder with said fluid passage on the side of saidcylinder opposite said restricted orifice being connected to the controlvalve.

9. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice for controlling the passage of fluid tosaid cylinder on one side of said piston, a fluid passage connected tosaid cylinder on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite saidrestricted orifice, a port in said chamber, a valve for controlling thepassage of fluid from said cylinder to said chamber, said valve beingadapted to be moved in one direction by said piston, resilient means fornormally urging said valve in a direction opposing movement thereof bysaid piston, and said valve having a passage connecting said cylinderwith said chamber, said valve having port means of progressivelyincreasing area as said valve is moved into said chamber by said pistonand port means in said chamber adapted to be connected to a hydraulicline, said restricted orifice being connected by a hydraulic line to thecontrol valve and the down side of a cylinder and said port in saidchamber being connected by a hydraulic line to the lift side of cylinderopposite said restricted orifice with said fluid passage on the side ofsaid cylinder being connected to the control valve.

l0. In a device of the type set forth, a cylinder, a piston in saidcylinder, a restricted orifice for controlling the passage of fluid tosaid cylinder on one side of said piston, a fluid passage connected tosaid cylinder on the opposite side of said piston, a chambercommunicating with said cylinder on the side thereof opposite saidrestricted orifice, a port in said chamber, a valve for controlling thepassage of fluid from said cylinder opposite said restricted orifice tosaid chamber, said valve being adapted to be moved in one direction bysaid piston, resilient means for normally urging said valve in adirection opposing movement thereof by said piston, and said valvehaving a passage connecting said cylinder with said chamber, said valvebeing adapted to be closed by said resilient means and opened by theforce of fluid in said cylinder from a hydraulic line and passingthrough said restricted orifice, said restricted orifice being connectedby a hydraulic line to the control valve and the down side of a cylinderand said port in said chamber being connected by a hydraulic line to thelift side of a cylinder with said fluid passage on the side of saidcylinder opposite said restricted orifice being connected to the controlvalve.

References Cited in the file of this patent UNITED STATES PATENTS2,588,520 Halgren et al Mar. 11, 1952

